JPS58107818A - Gas fuel injector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a fuel injector (
The present invention relates to a fuel injector (2) intended for injecting a range of gaseous fuels having different caloric values into the combustion chamber of an industrial gas turbine engine.

When operating an industrial gas turbine engine at idle, the combustion efficiency (η) varies as a function of the gaseous fuel velocity at the exit of the fuel injector. Combustion efficiency (η
) The curve of gaseous fuel velocity η has a peak where small changes in gaseous fuel velocity result in large decreases in combustion efficiency.

If the velocities of the various gaseous fuels and the compressor discharge air are more closely matched at the combustor inlet, the η vs. V curve at engine idle will not show a peak and the combustion efficiency will increase relative to the gaseous fuel velocity It has been found that sensitivity decreases. Since the engine must receive equal heat input per unit time regardless of the type of fuel used, the velocity of the gaseous fuel in the fuel delivery duct varies depending on the caloric value and density of the fuel. In this way, the flow rate must change depending on the fuel used, but since the duct area is constant, the gaseous fuel velocity must change. Therefore, high calorie gaseous fuel has a low discharge rate from the fuel discharge duct, and low (3) calorie gaseous fuel has a high discharge rate. Thus, the gaseous fuel velocity is approximately 80 fps (240 (1 m/s) to 1000 fps).
fps (80,0OOcrn/s), while the compressor discharge air velocity at engine idle varies between 400 and 600 fps (12,000 and 18.0 fps).
00cm, 7 seconds).

The present invention equalizes the velocities of various gaseous fuels and compressor discharge air at the inlet of an engine combustion chamber by adjusting the energy exchange between the fuel and air streams, or
This suggests matching to a closer value.

This energy exchange can be accomplished by mixing the gaseous fuel and air by a swirler device located centrally at the head of each combustion chamber. The swirler device may include several vanes and a central bintle that together define several curved passages of decreasing cross-sectional area in the direction of flow. These passages receive compressor discharge air from the engine compressor and gaseous fuel from the fuel discharge duct;
The outlet of the duct is located near the upstream end of the bottle, and (4) overlaps therewith, so that the gaseous fuel first enters the radially inner portion of the swirler passages and then the remainder of the length of each passage. It is designed to mix with compressor air.

An energy exchange occurs between the two streams and the velocity difference between them will result in either an increase in gaseous fuel velocity, an increase or decrease in air velocity, or a combination of these effects.

The overall effect is that the gaseous fuel and air flow at similar velocities and are at least partially mixed at the outlet from the swirler passage, which constitutes the inlet to the combustion chamber.

The device also includes a cuff with parallel walls and extending a short distance from the head of the combustion chamber into the combustion chamber at the outer periphery of the swirler assembly to improve the flow pattern in the primary zone. ) or sleeves. The cuff can have one or more rows of radial holes formed around its periphery.

Cuffs of this type have been described and claimed in other patent specifications (UK Patent No. 1,595,224, US Patent Application No. 1,23,260).

(5) The present invention will be described in more detail below with reference to the accompanying drawings.

In FIG. 1, a gas turbine engine power plant 10 is supplied with compressed air from a compressor 12.
several circumferentially arranged combustion chambers 14; a compressor-driven turbine 16 driven by the combustion products of the combustion chambers 14;
and a power turbine 18 that is driven by the residual energy of the exhaust from the turbine 16 to drive a load 20 .

The fuel for power plant 10 includes a range of gaseous fuels having different caloric values, and each combustion chamber 14 has a gaseous fuel injector 22. With particular reference to FIGS. 2, 8, and 4, each fuel injector 22 is connected to a gaseous fuel discharge duct 2.
4 and a swirler and bottle assembly 26 mounted in the central hole 28 of the combustion chamber head 30 for practical reasons. Assembly 26 could be attached to duct 24, but such an approach would require an extremely large opening in the engine casing and would make accurate positioning relative to the combustion chamber difficult (6).

Assembly 26 includes an array of evenly spaced serpentine vanes 32 extending between an outer housing or sleeve 34 and a hub or central bintle 36 .

The vanes are bent at an angle of approximately 80 degrees, although other angles may be used depending on the degree of rotation required, and the sleeve 34 is an extension of the central portion of the head 80. Alternatively, the sleeve can be a separate part from the head and attached to it by any suitable means, for example by brazing.

The vanes 82, sleeves 84 and bottle 86 have several passages 88 of decreasing cross-sectional area in the direction of flow as indicated by arrow B.
The vane 320 bends to change the direction of flow therethrough.

The outlet 40 of the discharge duct 24 is coaxial with the assembly 26;
The outlet end is positioned within a notch 42 formed in the radially second flow end of each vane 82 so that the outlet 40
overlaps the upstream end of the bottle 36.

Power plant 10 is arranged to work with a range of gaseous fuels having different densities and caloric values. In order to maintain a constant heat input per unit time for any particular engine operating condition, the flow rate of different gaseous fuels through duct 24 is different so that the exit velocity of different fuels will vary.

Speed change: Approximately 80 to 1000 f'p8 (2,4
00 to 80,000 m/s), with high caloric value fuels flowing at low velocities and low caloric value fuels flowing at high speeds. The velocity of the discharge air from the compressor 12 at the inlet of the assembly 260 is approximately 400-600 fp at engine idle.
s (12,ooo~18.oooLM/sec).

FIG. 5 shows a typical η vs. V curve, and if V is not near point H but in the area of point A or C, the combustion efficiency will be low. To achieve optimal efficiency, the outlet flow area of the gaseous fuel injector would have to be modified to match the respective caloric value and density.

In the device of the invention, the velocities of the gaseous fuel and the compressor (8) discharge air are matched to equal or close values at or near the sleeve and bottle assembly. Approximately 80~ depending on value and density
Gaseous fuel with a velocity in the range of l OOOfps (2,400 to 30,000 m/s) leaves outlet 40 and enters the radially inner portion of the upstream end of each passage 38, while compressor discharge air ~600 fp8 (12,0
00-18,000 cm/sec) into the radially outer portion of the upstream end of each passageway 38.

Because the gaseous fuel tends to mix with the air flow in each passageway, and because the cross-sectional area of each passageway is decreasing, there is a general tendency for the flow velocity in the passageways to increase. There is also an energy exchange between the fuel and air, and due to the difference in initial velocity, the fuel velocity increases,
Air velocity increases, decreases, or a combination of these effects.

When using the above types of fuel injectors, the engine
The η vs. V curve at idle does not have a peak as in FIG. 5, but is much flatter like the typical curve in FIG. 28 from 100 BTU/5 cf (89(9) Kcal/Nm') of coal extracted gas
1f3BTU/s c,f (2061Kcal/
This property, present in a wide range of gaseous fuels up to 100 lb-ft (Nm'') of propane, means that acceptable combustion efficiencies can be obtained relatively easily from a single design basis.

Some have one or more rows of holes 46 and some do not,
A cuff or sleeve 44 may also be provided on the sleeve assembly 26 to enhance flow regimes in the primary region. Such cuffs have been described and claimed in other patent specifications (UK Patent No. 1,595,224, US Patent Application No. 1,28,260).

[Brief explanation of the drawing]

1 shows a gas turbine engine power plant incorporating one or more fuel injectors according to the present invention; FIG. 2 is a detailed view of one of the fuel injectors of FIG. 1; and FIG. 3 is a detailed view of one of the fuel injectors of FIG. 4 is a detailed view showing a partial side view of the fuel injector swath (]0)-ra and bintle assembly shown in FIG. 2; FIG. Typical Combustion Efficiency (η) vs. Gaseous Fuel Velocity Curve at the Fuel Injector Exit at Engine Idle Conditions, Without a Fuel Injector According to the Invention, FIG.
A typical η vs. V curve at engine idle. 22... Injector 24... Duct 26...
Swara-bintle assembly 36...hub 32...vane Patent applicant
Rolls-Royce Limited (4 others) (11)

Claims (1)

Claims: (υ) having a gaseous fuel duct arranged to discharge gaseous fuel to a swirler assembly arranged to receive a flow of compressed air from a compressor of a gas turbine engine power plant; In a gaseous fuel injector for a gas turbine engine power plant: the swirler assembly has a plurality of swirler vanes disposed between an outer housing and an inner hub, the direction of flow passing between the vanes, the hub, and the housing; defining a plurality of passageways having a cross-sectional area that decreases to; gaseous fuel is injected into an upstream radially internal force portion of the passageway and compressed air enters an upstream radially external force portion of the passageway; (2) the outer housing has a sleeve with parallel walls, and the hub has a bottle that increases in cross-sectional area in a downstream direction and terminates in a steep base; Patent (1) The injector according to claim 1. (3) The outlet of the gaseous fuel duct is positioned in several notches, and the notches are formed in the upstream edge of the swirler blade. (4) The swirler assembly is integral with or attached to the combustion chamber of the power plant, and the gaseous fuel duct is connected to the swirler assembly. A fuel injector according to claim 1, wherein the fuel injector is mounted independently from the body. (5) the parallel-walled sleeve extends from a downstream end of the outer circumference of the swarmer assembly so as to substantially form a limb. the sleeve is adapted to extend into the primary area of the combustion chamber of the power plant;
A fuel injector according to claim 1.